GB/T 8163 Seamless Steel Pipe Standard

I. Overview of GB/T 8163 Seamless Steel Pipes for Fluid Transportation Standard

GB/T 8163 is a Chinese national standard for seamless steel pipes for fluid transportation, used to carry general fluids such as water, oil, and gas, and applicable to various industrial, engineering, and equipment piping systems.

II. Comparison Table of Main Materials/Grades in GB/T 8163

Material Grade	Type	Chemical Composition Features	Mechanical Properties Features	Key Differences / Remarks
10#	Carbon Structural Steel	Low carbon content, few impurities	Lower strength, good plasticity, easy to process	Suitable for low-pressure, cost-sensitive applications; lowest strength, best ductility
20# (Most Common)	Carbon Structural Steel	Medium strength, stable composition	Tensile strength ~410–550 MPa, good weldability	Most commonly used in GB/T 8163; cost-effective with balanced performance
Q345 (A/B/C)	Low-Alloy High-Strength Steel	Contains trace Nb/V/Ti, increased strength	Yield ≥345 MPa, high pressure resistance	Significantly stronger than 10# and 20#; thinner wall can be chosen for same specifications to reduce weight
Q390 / Q420	Low-Alloy High-Strength Steel	More alloying, higher strength	Yield 390–420 MPa, higher pressure resistance	Higher strength, but reduced weldability and machinability; higher cost
15CrMo (Alloy Steel)	Cr-Mo Alloy Steel	Heat and pressure resistant	High-temperature strength, creep resistance	Suitable for high-temperature service; preferred for high-temperature, high-pressure environments
12Cr1MoV	Alloy Steel	Contains Cr, Mo, V; excellent temperature resistance	Good long-term high-temperature stability	Better temperature resistance than 15CrMo; slightly higher cost
35 / 45#	Structural Steel	High strength	High tensile strength, poor weldability	Often used for structural parts; not recommended for long-distance fluid pipelines
ST45 / ST52 (Equivalent foreign grades)	High-Strength Steel	Refer to DIN/EN composition	High strength, moderate plasticity	Commonly matched with GB/T 8163 in export projects

III. GB/T 8163 Chemical Composition and Mechanical Properties of Seamless Steel Pipes for Fluid Transportation

i. Chemical Composition Table

Material	C (%)	Mn (%)	Si (%)	S (%) ≤	P (%) ≤	Cr (%)	Mo (%)	V (%)
10#	0.07–0.13	0.35–0.65	≤0.35	0.035	0.035	—	—	—
20# (Most Common)	0.17–0.23	0.35–0.65	≤0.35	0.035	0.035	—	—	—
Q345	≤0.18	1.0–1.6	0.20–0.50	0.035	0.035	—	—	Nb/V/Ti trace
15CrMo	0.12–0.18	0.40–0.70	0.30–0.60	0.030	0.030	0.80–1.10	0.45–0.60	—
12Cr1MoV	0.08–0.15	0.40–0.70	0.17–0.37	0.030	0.030	0.90–1.20	0.25–0.35	0.15–0.30

ii. Mechanical Properties Table

Material	Yield Strength ReL (MPa) ≥	Tensile Strength Rm (MPa)	Elongation A (%) ≥	Features
10#	195	315–430	32	Soft, easy to bend and process
20# (Most Common)	245	410–550	26	Suitable for water, oil, and gas pipelines
Q345	345	470–630	20	High strength, used for higher pressure or structural applications
15CrMo	310	470–630	17	Good high-temperature and high-pressure performance
12Cr1MoV	275	440–600	18	Best high-temperature creep performance

IV. GB/T 8163 Specifications and Dimensions of Seamless Steel Pipes for Fluid Transportation

i. Small Diameter Fluid Pipes (10.3–60.3 mm)

Outer Diameter OD (mm)	Wall Thickness WT Range (mm)
10.3	1.8–3.0
13.7	1.8–3.0
17.2	1.8–3.5
21.3	2.0–4.0
26.9	2.0–4.5
33.4	2.5–5.0
42.3	2.5–6.0
48.3	2.5–6.0
60.3	3.0–8.0

ii. Commonly used medium-diameter sizes (73–168 mm)

Outer Diameter OD (mm)	Wall Thickness WT Range (mm)
73.0	3.5–10
76.1	3.5–10
88.9	4.0–12
101.6	4.0–14
108	4.0–14
114.3	4.0–14
121	4.0–14
133	4.5–16
139.7	4.5–16
159	5–18
168.3	5–20

iii. Large-diameter fluid pipes (≥ 219 mm)

Outer Diameter OD (mm)	Wall Thickness WT Range (mm)
219	6–25
245	6–25
273	6–30
325	6–30
355.6	8–30
377	8–32
406.4	8–36
426	8–36
457	8–40
508	8–45
530	8–50
559	10–50
610	10–60

V. Production Process

Round tube blank → Heating → Piercing → Rolling → Sizing/Reduction → Cooling → Cutting → Heat treatment (if required) → Surface treatment → Inspection → Finished product

VI. GB/T 8163 Quality Inspection Standard for Seamless Steel Pipes for Fluid Transportation

Inspection Item	Test Method / Standard	Acceptance Criteria (According to GB/T 8163)
Chemical Composition	Spectral Analysis (OES) or Chemical Analysis	Must meet the chemical composition requirements of the corresponding steel grade (10#, 20#, Q345, 15CrMo, etc.)
Mechanical Properties	Tensile Test (GB/T 228)	Yield strength, tensile strength, and elongation must meet the standard values of the corresponding steel grade (e.g., 20#: ReL ≥245 MPa, Rm 410–550 MPa)
Impact Test (for Low Alloy Steel)	Charpy Impact Test (GB/T 229)	Q345 and similar grades must meet the specified impact energy (room temperature ≥27 J)
Hydrostatic Test / Pressure Test	GB/T 241	Must withstand the specified pressure without leakage or rupture (P ≥ standard value, generally ≥20 MPa, calculated according to WT/OD)
Nondestructive Testing (UT/ET)	Ultrasonic Test or Eddy Current Test (GB/T 7735, GB/T 5777)	No cracks, slag inclusions, delaminations, or harmful defects are allowed
Surface Quality	Visual Inspection (GB/T 8163)	Pipe surface must be free of cracks, folds, laps, delaminations, weld overlaps, scars, etc.; minor scratches allowed locally but must be within tolerance
Dimensional Measurement	Calipers, Wall Thickness Gauge, Steel Tape	OD, WT, length, and tolerances must comply with GB/T 8163 requirements (OD ±1%, WT -12.5% or ±10%, etc.)
Ovality Check	OD Measurement	Ovality must be within OD tolerance range (usually ≤1%)
End Inspection	Visual + Caliper	Plain ends must be smooth and burr-free; bevel angle 30° ±2.5°, blunt edge 1.6 ±0.8 mm
Straightness (Bending)	GB/T 8163 Straightness Test	Overall bending ≤1.5‰; local bending ≤3 mm/m
Weight Deviation	Theoretical Weight Comparison	Weight deviation must meet the standard (generally ±10%)
Pipe End Seal (Threaded Pipe)	Thread Gauge Inspection	Threads must meet G pressure thread requirements; no cross-threading or damage

VII. GB/T 8163 Application Areas of Seamless Steel Pipes for Fluid Transportation

Application	Typical Medium / Working Condition	Why Choose GB/T 8163 (Advantages)	Common Steel Grades
Industrial Fluid Transport	Water, oil, gas, compressed air, inert gases	Seamless structure provides stability, high pressure resistance, good weldability	20, Q345
Boiler Room & Heat Exchange Piping	Hot water, steam systems (≤350°C)	Good pressure and temperature resistance, suitable for thermal cycles	20, Q345B
Petrochemical Pipelines	Chemical media, light oils, water injection systems	High strength, corrosion resistance can be enhanced with internal coatings	20, Q345, Q345E
Urban Infrastructure	Tap water, fire-fighting networks, pressurized water supply	High reliability and long service life of seamless steel pipes	20
Mechanical Equipment Piping	Hydraulic oil, lubricating oil, machine cooling water	Uniform wall thickness, good machinability, suitable for mechanical piping	20, Q345
Mining & Tunnel Engineering	High-pressure water supply, drainage, grouting systems	Impact and pressure resistant, suitable for harsh environments	Q345B / Q345E
Marine & Port Engineering	Seawater pipelines, anti-corrosion transport systems	High strength and corrosion resistance, external anti-corrosion layer can be applied	Q345E
Power Plant Auxiliary Piping	Industrial water, circulating water, oil systems	Moderate cost, stable performance	20, Q345B

VIII. GB/T 8163 Selection Guide for Seamless Steel Pipes

Selection Dimension	Key Considerations	Recommended Choice / Notes
Medium Type	Water, air, oil, gas, chemical liquids	For water and air: 20#; for oil or light chemical liquids: 20# or Q345; highly corrosive media require internal coating or low-alloy steel
Working Pressure	Medium to low pressure, pressure > 2 MPa	Medium/low pressure pipelines: 20#; high pressure or large diameter: Q345 (wall thickness can be reduced)
Operating Temperature	Normal, medium, high	Normal ≤100°C: carbon steel; medium ≤300°C: Q345 recommended; high-temperature steam or boiler systems: 15CrMo or 12Cr1MoV
Pipe Diameter & Wall Thickness	Diameter size and wall thickness matching pressure	Small diameter ≤60 mm: wall thickness 2–8 mm; large diameter ≥219 mm: 8–60 mm, calculated based on design pressure
Installation Method	Welding, threaded, socket	Welded pipelines: plain / beveled ends; small diameter fast installation: threaded ends; frequent assembly/disassembly: socket ends
Environmental Conditions	Indoor, outdoor, seaside, low temperature	Indoor dry: black steel; outdoor/humid: hot-dip galvanized or epoxy-coated; marine/port: Q345E + 3PE / epoxy zinc-rich coating
Corrosion Resistance	Contact with acidic/alkaline or corrosive fluids	General water/oil: carbon steel; highly corrosive fluids: low-alloy steel or additional anti-corrosion coating (FBE / 3PE / epoxy)
Length Requirements	Reduce welds, facilitate transport	Longer lengths reduce welds: choose 12 m or multiples; short pipes or transport-limited: 4–6 m
Cost Efficiency	Cost vs performance	Standard low-pressure water pipes: 20# offers best cost-performance; high pressure or high-temperature: consider low-alloy or alloy steel